The present invention relates to a data processing device such as electronic typewriter, word processor and computer.
In conventional data processing devices, there is usually provided PS (proportional spacing) printing facility for printing PS type such as "i" and "w" with a greater or smaller moving distance of a printing head than for the standard type, but such PS characters are displayed on a screen display at an equal column spacing as for standard characters.
With the above data processing devices, the character display position on the display screen is out of alignment with the actual printing position, so that it is necessary to provide some way of supplying the operator with an actual printing image thereof.
As one measure for this, the printing position can be numerically shown on the display screen, however it is difficult to grasp digital information by way of an image. It has been therefore proposed to display a scale S, as illustrated in FIGS. 8 to 12, showing the input range of one line, on which the printing position is indicated by a scale cursor SK. Each dot of the scale S indicates a column of standard printing spacing and every tenth dot is marked with scale figures. The scale cursor SK is placed on the column which is specified by dividing the sum of character spacings on one line by the standard printing spacing and adding 1 to the quotient.
For instance, assuming that the standard printing space is 10 pitch (1 pitch=1/20 inch), let us input 10 characters of standard 10-pitch printing spacing (such as A, B, C and D). The scale cursor SK is then positioned on the same column (column 11) on the display screen as the text cursor TK indicating the input position of the characters, as illustrated in FIG. 8.
When, on the other hand, 10 characters of 16-pitch spacing (such as W) are entered, the text cursor TK is positioned on the column 11, while the scale cursor SK is on the column 17 (=16.times.10.div.10+1) as illustrated in FIG. 9.
When 10 characters of 6-pitch spacing (such as i) are entered, the text cursor TK is positioned on the column 11, while the scale cursor SK is on the column 7 (=6.times.10.div.10+1) as illustrated in FIG. 10.
Consequently, when multiple texts including a number of PS types are entered into one line, the scale cursor SK is likely to go outside the display screen.
Assuming, for instance, a device in which one line accepts data input of 254 columns is provided with a display medium (e.g. CRT) having a display width of 80 columns, when 150 of the characters "W" are entered, the text cursor TK is placed on the column 151 of the display screen as illustrated in FIG. 11. The scale cursor SK, on the other hand, goes to column 241 (=16.times.150.div.10+1) which is ahead of the text cursor TK by 90 columns, so that the display screen is unable to display the scale cursor SK.
When 230 of the characters "i" are entered, while the text cursor TK is positioned on column 231 on the screen as illustrated in FIG. 12, the scale cursor SK is on column 139 (=6.times.230.div.10+1) which is behind the text cursor TK by 92 columns. As a result, the screen no longer allows display of the scale cursor SK.
On the other hands, in conventional data processing devices, when the formatting mode is entered to change the format during editing a text, shifting the text cursor causes the whole text on the display screen to horizontally scroll at one time.
Therefore, problems have been encountered that operators troubled by disturbing screen flickering, and such as some time is required for processing using an internal circuit as of microprocessor to scroll the whole text and re-edit it, which causes some time lag in entering the next keystroke, resulting in a longer time required for editing operation.